Annular combustors often are used with gas turbine engines. Generally described, an annular combustor may have a number of individual can combustors that are circumferentially spaced between a compressor and a turbine. Each can combustor separately generates combustion gases that are directed downstream towards the first stage of the turbine.
The mixing of these separate combustion streams is largely a function of the free stream Mach number at which the mixing is taking place as well as the differences in momentum and energy between the combustion streams. Moreover, a stagnant flow region or wake in a low flow velocity region may exist downstream of a joint between adjacent can combustors due to the bluntness of the joint. As such, the non-uniform combustor flows may have a Mach number of only about 0.1 when leaving the can combustors. Practically speaking, the axial distance between the exit of the can combustors and the leading edge of a first stage nozzle is relatively small such that little mixing actually may take place before entry into the turbine.
The combustor flows then may be strongly accelerated in the stage one nozzle to a Mach number of about 1.0. This acceleration may exaggerate the non-uniformities in the flow fields and hence create more mixing losses downstream thereof. As the now strongly nonuniform flow field enters the stage one bucket, the majority of mixing losses may take place therein as the wakes from the can combustor joints may be mixed by an unsteady flow process.
There is thus a desire therefore for an improved combustor design that may minimize mixing loses. Such reduced mixing loses may reduce overall pressure losses without increasing the axial distance between the combustor and the turbine. Such an improved combustion design thus should improve overall system performance and efficiency.